U.S. patent application number 17/252353 was filed with the patent office on 2021-09-02 for casting apparatus and method for the production of a cast sheet of a material containing alkaloids.
The applicant listed for this patent is PHILIP MORRIS PRODUCTS S.A.. Invention is credited to Rui Nuno Batista, Silvia Capo, Chiara Fasciani.
Application Number | 20210267260 17/252353 |
Document ID | / |
Family ID | 1000005637087 |
Filed Date | 2021-09-02 |
United States Patent
Application |
20210267260 |
Kind Code |
A1 |
Capo; Silvia ; et
al. |
September 2, 2021 |
CASTING APPARATUS AND METHOD FOR THE PRODUCTION OF A CAST SHEET OF
A MATERIAL CONTAINING ALKALOIDS
Abstract
The invention relates to a casting apparatus (100) to cast a
sheet of a material containing alkaloids, the casting apparatus
including: a casting box (10) apt to contain a slurry (18) to be
cast to form the sheet; a slurry supply element (5) defining a
feeding channel (15) apt to introduce the slurry into the casting
box in a supply direction; path diverting fins (19, 20) positioned
within the feeding channel, the path diverting fins being apt to
come into contact with the slurry inside the feeding channel; a
movable support (2); and a casting blade (1) apt to cast the slurry
contained in the casting box onto the movable support so as to form
the cast sheet. The invention relates also to a method to cast a
sheet of a material containing alkaloids.
Inventors: |
Capo; Silvia;
(Capaccio-Paestum (SA), IT) ; Fasciani; Chiara;
(Avekzzano, IT) ; Batista; Rui Nuno; (Morges,
CH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
PHILIP MORRIS PRODUCTS S.A. |
Neuchatel |
|
CH |
|
|
Family ID: |
1000005637087 |
Appl. No.: |
17/252353 |
Filed: |
June 28, 2019 |
PCT Filed: |
June 28, 2019 |
PCT NO: |
PCT/EP2019/067454 |
371 Date: |
December 15, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A24C 5/01 20200101; A24B
3/14 20130101; A24B 15/14 20130101 |
International
Class: |
A24B 3/14 20060101
A24B003/14; A24C 5/01 20060101 A24C005/01 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 29, 2018 |
EP |
18181033.4 |
Claims
1-15. (canceled)
16. A casting apparatus to cast a sheet of a material containing
alkaloids, the casting apparatus including: a casting box apt to
contain a slurry to be cast to form the sheet; a slurry supply
element defining a feeding channel apt to introduce the slurry into
the casting box in a supply direction; path diverting fins
positioned within the feeding channel, the path diverting fins
being apt to come into contact with the slurry inside the feeding
channel, wherein the path diverting fins comprise a plurality of
curved fins arranged in at least one row and wherein the curved
fins of a same row have equally oriented concavity; a movable
support; and a casting blade apt to cast the slurry contained in
the casting box onto the movable support so as to form the cast
sheet.
17. The casting apparatus according to claim 16, wherein the slurry
supply element includes a tapered portion.
18. The casting apparatus according to claim 17, wherein the path
diverting fins are positioned downstream the tapered portion in the
supply direction.
19. The casting apparatus according to claim 16, wherein the
feeding channel defines a channel width and the path diverting fins
are distributed along the width of the channel.
20. The casting apparatus according to claim 16, wherein the
casting box includes sidewalls and the slurry supply element
defines an inlet for the slurry, the inlet for the slurry being
formed in one of the lateral walls.
21. The casting apparatus according to claim 16, wherein the slurry
supply element defines an inlet for the slurry, the inlet for the
slurry being positioned above or at a top portion of the casting
box.
22. A method to cast a sheet of a material containing alkaloids,
the method comprising: providing a casting box; providing a casting
blade connected to the casting box; providing a movable support
facing the casting blade; providing a slurry supply element
defining a feeding channel; providing path diverting fins
positioned within the feeding channel; introducing the slurry into
the casting box along a supply direction trough the feeding
channel; casting the slurry on the movable support by means of the
casting blade; and adjusting an orientation of the path diverting
fins with respect to the supply direction depending on parameters
of the slurry or of the cast sheet.
23. The method according to claim 22, wherein the step of feeding
the slurry inside the casting box comprises introducing the slurry
in the casting box along a supply direction forming an angle with a
horizontal plane comprised between about -45 degrees and about +45
degrees.
24. The method according to claim 22, wherein the step of feeding
the slurry inside the casting box comprises introducing the slurry
in the casting box along a supply direction forming an angle with a
vertical plane comprised between about -15 degrees and about +15
degrees.
25. The method according to claim 22 comprising adjusting a
position of the path diverting fins shifting the path diverting
fins along the supply direction depending on parameters of the
slurry or of the cast sheet.
26. The method according to claim 22, wherein the cast sheet of a
material containing alkaloids includes a homogenized tobacco sheet.
Description
[0001] This invention relates to a casting apparatus and method for
producing a cast web of a material containing alkaloids.
[0002] In particular, the material containing alkaloids is
homogenized tobacco material, preferably used in an
aerosol-generating article such as, for example, a cigarette or a
"heat-not-burn" type tobacco containing product.
[0003] Today, in the manufacture of tobacco products, besides
tobacco leaves, also homogenized tobacco material is used. This
homogenized tobacco material is typically manufactured from parts
of the tobacco plant that are less suited for the production of cut
filler, like, for example, tobacco stems or tobacco dust.
Typically, tobacco dust is created as a side product during the
handling of the tobacco leaves during manufacture.
[0004] The most commonly used forms of homogenized tobacco material
are reconstituted tobacco sheet and cast leaf (TCL is the acronym
for tobacco cast leaf). The process to form homogenized tobacco
material sheets commonly comprises a step in which tobacco dust and
a binder, are mixed to form a tobacco slurry. The slurry is then
used to create a tobacco web, for example by casting a viscous
slurry onto a moving metal belt to produce so called cast leaf.
Alternatively, a slurry with low viscosity and high water content
can be used to create reconstituted tobacco in a process that
resembles paper-making. Once prepared, homogenized tobacco webs may
be cut in a similar fashion as whole leaf tobacco to produce
tobacco cut filler suitable for cigarettes and other smoking
articles. A process for making such homogenized tobacco is for
example disclosed in European Patent EP 0565360.
[0005] In a "heat-not-burn" aerosol-generating article, an
aerosol-forming substrate is heated to a relatively low
temperature, in order to form an aerosol but prevent combustion of
the tobacco material. Further, the tobacco present in the
homogenized tobacco material is typically the only tobacco, or
includes the majority of the tobacco, present in the homogenized
tobacco material of such a "heat-not burn" aerosol-generating
article. This means that the aerosol composition that is generated
by such a "heat-not burn" aerosol-generating article is
substantially only based on the homogenized tobacco material.
Therefore, it is important to have good control over the
composition of the homogenized tobacco material, for the control
for example, of the taste of the aerosol.
[0006] Due to variations in the physical properties of the slurry,
for example, consistency, viscosity, fibre size, particle size,
moisture or the age of the slurry, standard casting methods and
apparatus may result in unintended variations in the application of
the slurry onto a support during the casting of web of homogenized
tobacco. A non-optimal casting method and apparatus may lead to
inhomogeneity and defects of the cast web of homogenized
tobacco.
[0007] Inhomogeneity in the homogenized tobacco web may lead to
difficulties in subsequent handling of the homogenized tobacco web
in the production of the aerosol-generating article. For example,
inhomogeneity may lead to tearing or even rupture of the web during
manufacture or further processing of the web. This in turn could,
for example, result in machine stops. Additionally, an
inhomogeneous tobacco web may create unintended difference in the
aerosol delivery between aerosol generating articles that are
produced from the same homogenized tobacco web.
[0008] There is a need for a casting apparatus and method for the
production of a cast web of a material containing alkaloids that is
adapted to overcome, or at least decrease, the above-mentioned
issue.
[0009] The invention relates to a casting apparatus to cast a sheet
of a material containing alkaloids, the casting apparatus
including: a casting box apt to contain a slurry to be cast to form
the sheet; a slurry supply element defining a feeding channel apt
to introduce the slurry into the casting box in a supply direction;
path diverting fins positioned within the feeding channel, the path
diverting fins being apt to come into contact with the slurry
inside the feeding channel; a movable support; and a casting
element apt to cast the slurry contained in the casting box onto
the movable support so as to form the cast sheet.
[0010] The proposed casting apparatus aims to achieve a uniform
slurry deposition on the movable support. The presence of the fins
in the flow path of the slurry increases the mixing of the slurry
when it enters the casting box. The flow of slurry may be directed
to the casting box via different pipes or distributors and the fins
may turn the different flows, one per pipe or distributor, into a
single homogenized flow which enters the casting box.
[0011] Preferably, the casting element is a casting blade.
Homogeneity of the slurry is of particular importance when the
slurry, in order to be casted, has to flow through a gap formed
between the blade and the movable support.
[0012] As used herein, the terms "sheet" denotes a laminar element
having a width and length substantially greater than the thickness
thereof. The width of a sheet is preferably greater than about 10
millimeters, more preferably greater than about 20 millimeters or
about 30 millimeters. Even more preferably, the width of the sheet
is comprised between about 100 millimeters and about 300
millimeters. A continuous "sheet" is herein called "web".
[0013] As used herein, the term "casting blade" denotes a
longitudinally shaped element that may have an essentially constant
cross-section along major parts of its lengthwise extension. It
shows at least one edge that is intended to come into contact with
a pasty, viscous or liquid-like substance to be influenced by said
edge, such as a slurry. Said edge may have a sharp and knife-like
shape. Alternatively, it may have a rectangular or a rounded
shape.
[0014] As used herein, the term "movable support" denotes any means
comprising a surface that can be moved in at least one longitudinal
direction. The movable support may form a closed loop so to provide
an uninterrupted transporting ability in one direction. However,
the movable support may be moved in back and forth moving way as
well. The movable support may include a conveyor belt. The movable
support may be essentially flat and may show a structured or an
unstructured surface. The movable support may show no openings in
its surface or may show only orifices of such a size that they are
impenetrable for the slurry deposited on it. The movable support
may comprise a sheet-like movable and a bendable band. The band may
be made of a metallic material, including but not limited to steel,
copper, iron alloys and copper alloys, or a rubber material. The
band may be made of a temperature-resistant material so that it can
be heated to speed up the drying process of the slurry.
[0015] As used herein, the term "slurry" denotes a liquid-like,
viscous or pasty material that may comprise an emulsion of
different liquid-like, viscous or pasty material and that may
contain a certain amount of solid-state particles, provided that
the slurry still shows a liquid-like, viscous or pasty
behaviour.
[0016] A "material containing alkaloids" is a material which
contains one or more alkaloids. The alkaloids may comprise
nicotine. The nicotine may be found, for example, in tobacco.
[0017] Alkaloids are a group of naturally occurring chemical
compounds that mostly contain basic nitrogen atoms. This group also
includes some related compounds with neutral and even weakly acidic
properties. Some synthetic compounds of similar structure are also
termed alkaloids. In addition to carbon, hydrogen and nitrogen,
alkaloids may also contain oxygen, sulfur and, more rarely, other
elements such as chlorine, bromine, and phosphorus.
[0018] Alkaloids are produced by a large variety of organisms
including bacteria, fungi, plants, and animals. They can be
purified from crude extracts of these organisms by acid-base
extraction. Caffeine, nicotine, theobromine, atropine, tubocurarine
are examples of alkaloids.
[0019] As used herein, the term "homogenised tobacco material"
denotes material formed by agglomerating particulate tobacco, which
contains the alkaloid nicotine. The material containing alkaloids
can thus be a homogenized tobacco material.
[0020] The most commonly used forms of homogenized tobacco material
is reconstituted tobacco sheet and cast leaf. The process to form
homogenized tobacco material sheets commonly comprises a step in
which tobacco dust and a binder, are mixed to form a slurry. The
slurry is then used to create a tobacco web. For example by casting
a viscous slurry onto a moving metal belt to produce so called cast
leaf. Alternatively, a slurry with low viscosity and high water
content can be used to create reconstituted tobacco in a process
that resembles paper-making.
[0021] The homogenized tobacco sheet material can be also referred
to as a reconstituted sheet material and formed using particulate
tobacco (for example, reconstituted tobacco) or a tobacco
particulate blend, a humectant and an aqueous solvent to form the
tobacco composition. This tobacco composition may be then casted,
extruded, rolled or pressed to form a sheet material from the
tobacco composition. The sheet of tobacco can be formed utilizing a
wet process, where tobacco fines are used to make a paper-like
material; or a cast leaf process, where tobacco fines are mixed
together with a binder material and cast onto a moving belt to form
a sheet.
[0022] The homogenized tobacco sheet generally includes, in
addition to the tobacco, a binder and an aerosol-former, such as
guar and glycerin.
[0023] As used herein, the term "aerosol forming material" denotes
a material that is capable of releasing volatile compounds upon
heating to generate an aerosol. Tobacco, together with other
compounds, may be classified as an aerosol forming material,
particularly a sheet of homogenized tobacco comprising an aerosol
former. An aerosol forming substrate may comprise or consist of an
aerosol forming material. The homogenized tobacco sheet can be used
as an aerosol forming material.
[0024] The slurry may comprise a number of different components or
ingredients. These components may influence the properties of the
cast web of material containing alkaloids. A first ingredient is a
material containing alkaloids, for example in powder form. This
material can be for example a tobacco powder blend, which
preferably contains the majority of the tobacco present in the
slurry. The tobacco powder blend is the source of the majority of
tobacco in the homogenized tobacco material and thus gives the
flavor to the final product, for example to an aerosol produced
heating the homogenized tobacco material. A cellulose pulp
containing cellulose fibers is preferably added to the slurry in
order to increase the tensile strength of the alkaloids material
web, acting as a strengthening agent. A binder may be added. An
aerosol-former may be added. Binder and aerosol-former are
preferably added in order to enhance the tensile properties of the
homogenized sheet and promote the formation of aerosol. Further, in
order to reach a certain viscosity and moisture optimal for casting
the web of material containing alkaloids, water may be added to the
slurry.
[0025] The quantity of binder added to the slurry may be comprised
between about 1 percent and about 5 percent in dry weight of the
slurry. More preferably, it is comprised between about 2 percent
and about 4 percent. The binder used in the slurry may be any of
the gums or pectins described herein. The binder may ensure that
the tobacco powder remains substantially dispersed throughout the
homogenized tobacco web. Although any binder may be employed,
preferred binders are natural pectins, such as fruit, citrus or
tobacco pectins; guar gums, such as hydroxyethyl guar and
hydroxypropyl guar; locust bean gums, such as hydroxyethyl and
hydroxypropyl locust bean gum; alginate; starches, such as modified
or derivitized starches; celluloses, such as methyl, ethyl,
ethylhydroxymethyl and carboxymethyl cellulose; tamarind gum;
dextran; pullalon; konjac flour; xanthan gum and the like. The
particularly preferred binder for use in the present invention is
guar.
[0026] The introduction of cellulose fibres in the slurry typically
increases the tensile strength of the tobacco material web, acting
as a strengthening agent. Therefore, adding cellulose fibres may
increase the resilience of the homogenized tobacco material web.
Cellulose fibres for including in a slurry for homogenized tobacco
material are known in the art and include, but are not limited to:
soft-wood fibres, hard wood fibres, jute fibres, flax fibres,
tobacco fibres and combination thereof. In addition to pulping, the
cellulose fibres might be subjected to suitable processes such as
refining, mechanical pulping, chemical pulping, bleaching, sulphate
pulping and combination thereof. Cellulose fibres may include
tobacco stem materials, stalks or other tobacco plant material.
Preferably, cellulose fibres such as wood fibres comprise a low
lignin content. Alternatively fibres, such as vegetable fibres, may
be used either with the above fibres or in the alternative,
including hemp and bamboo. The length of cellulose fibres is
advantageously between about 0.2 millimetres and about 4
millimetres. Preferably, the mean length per weight of the
cellulose fibres is between about 1 millimetre and about 3
millimetres. Further, preferably, the amount of the cellulose
fibres is comprised between about 1 percent and about 7 percent in
dry weight basis of the total weight of the slurry (or homogenized
tobacco sheet).
[0027] Suitable aerosol-formers for inclusion in slurry for
homogenised tobacco material are known in the art and include, but
are not limited to: monohydric alcohols like menthol, polyhydric
alcohols, such as triethylene glycol, 1,3-butanediol and glycerine;
esters of polyhydric alcohols, such as glycerol mono-, di- or
triacetate; and aliphatic esters of mono-, di- or polycarboxylic
acids, such as dimethyl dodecanedioate and dimethyl
tetradecanedioate.
[0028] Examples of preferred aerosol-formers are glycerine and
propylene glycol.
[0029] The slurry may have an aerosol-former content of greater
than about 5 percent on a dry weight basis. The slurry may have an
aerosol former content of between about 5 percent and about 30
percent by weight on a dry weight basis. More preferably, the
aerosol-former is comprised between about 10 percent to about 25
percent of dry weight of the slurry. More preferably, the
aerosol-former is comprised between about 15 percent to about 25
percent of dry weight of the slurry.
[0030] The binder and the cellulose fibers are preferably included
in a weight ratio comprised between about 1:7 and about 5:1. More
preferably, the binder and the cellulose fibers are included in a
weight ratio comprised between about 1:1 and about 3:1.
[0031] The binder and the aerosol-former are preferably included in
a weight ratio comprised between about 1:30 and about 1:1. More
preferably, the binder and the aerosol-former are included in a
weight ratio comprised between about 1:20 and about 1:4.
[0032] Preferably, the alkaloid containing material is tobacco. The
binder and the tobacco particles are preferably included in a
weight ratio comprised between about 1:100 and about 1:10. More
preferably, the binder and the tobacco particles are included in a
weight ratio comprised between about 1:50 and about 1:15, even more
preferably between about 1:30 and 1:20.
[0033] The aerosol-former and the tobacco particles are preferably
included in a weight ratio comprised between about 1:20 and about
1:1. More preferably, the aerosol-former and the tobacco particles
are included in a weight ratio comprised between about 1:6 and
about 1:2.
[0034] The aerosol former and the cellulose fibres are preferably
included in a weight ratio comprised between about 1:1 and about
30:1. More preferably, the aerosol-former and the cellulose fibres
are included in a weight ratio comprised between about 5:1 and
about 15:1.
[0035] The cellulose fibres and the tobacco particles are
preferably included in a weight ratio comprised between about 1:100
and about 1:10. More preferably, the cellulose fibres and the
tobacco particles are preferably included in a weight ratio
comprised between about 1:50 and about 1:20.
[0036] The apparatus of the invention includes a casting box to
contain the slurry and a movable support where the slurry is cast
using a casting element. The casting element is a casting blade.
The movable support in its movement defines a casting
direction.
[0037] The slurry may reach the casting box from a different
location. The casting box therefore might not be the place where
the slurry is formed. For example, the slurry may be created in a
silo, from where it is transferred to the casting box via suitable
piping. Preferably, the slurry is continuously supplied to the
casting box while the slurry is cast onto the movable support to
form a continuous web of material containing alkaloids. The silo
and the casting box are thus preferably fluidly connected in order
to allow the slurry flow from one to the other.
[0038] The casting-box is preferably box-shaped. Preferably, the
casting box includes walls. More preferably, the walls in turn
comprise sidewalls. The sidewalls may include a first and a second
couple of opposite sidewalls, called first, second sidewalls in the
first couple, and third and fourth sidewalls in the second couple.
The sidewalls are preferably advantageously substantially vertical,
or tilted with respect to a vertical plane. First and second
sidewalls, and third and fourth sidewalls, are respectively one
facing the other. Preferably, the walls of casting box also include
a bottom wall. The bottom wall may include an aperture. Preferably,
the whole bottom part of the casting box defines an aperture. The
bottom wall, alternatively, can be completely closed.
[0039] The casting box may include a closed top wall or a lid, or
the top wall can include an aperture. In case of a lid, it can be
fixed, or movable. In the latter case, the lid might be slidable on
the sidewalls of the casting box.
[0040] The walls of the casting box define an inner volume of the
casting box itself, that is, the walls delimit an inner volume of
the casting box. As mentioned, the casting box may include an
aperture, for example in a bottom or top area, so that the box is
not a completely closed container. The aperture is provided to cast
the slurry. The inner volume of the casting box is thus in contact
with the outside. Due to the presence of the aperture, the inner
volume of the casting box is considered as the volume of a
"theoretical" box where the area defined by the aperture is closed.
The demarcation line between the inner volume of the box and the
outside is therefore preferably made by considering the aperture
closed by a wall. The aperture may be formed in more than one wall
(for example, corner apertures, which are apertures formed at the
corners of the box). Further, more than a single aperture might be
present.
[0041] The casting blade is preferably arranged perpendicular to
the casting direction. The web of material is formed by means of
the casting blade that casts the slurry present in the casting box
into the movable support. The casting box has preferably an opening
in the bottom part and the movable support is positioned partly
below the aperture. The slurry from the casting box comes into
contact with the casting blade at the aperture. An edge of the
casting blade forms a gap with the surface of the movable support
and the slurry passes through the aperture defined by said gap. The
thickness of the cast web of material may be determined by the
distance, among others, between the edge of the casting blade that
comes into contact with the slurry and the surface of the movable
support, that is, by the dimension of the above defined gap.
[0042] In a different embodiment, the casting element includes a
casting roller. In this embodiment, the casting box has preferably
an aperture in the top part, and the movable support and the
casting roller are both positioned facing the aperture and facing
each other. Rotation of the roller, which is at least partly
immerged in the slurry, causes a film of slurry to be casted onto
the movable support. A gap is present between the casting roller
and the movable support. The thickness of the cast web of material
may be determined by the distance, among others, between the outer
surface of the casting roller and the outer surface of the movable
support, that is by the dimension of the above defined gap.
[0043] The slurry enters the casting box through a slurry supply
element, which defines a supply channel. The supply channel is
preferably as wide as the casting box, or slightly smaller, so that
the slurry is deposited or enters substantially uniformly over the
whole dimension of the casting box to minimize local increase of
the slurry level. The width is considered as a dimension
perpendicular to the casting direction. The supply channel defines
an inlet for the slurry, corresponding to the outlet of the supply
channel from which the slurry exits. This inlet is preferably
oblong. The supply channel might be considered as a pipe having an
oblong, such as oval or rectangular, cross section. To the supply
channel, a single pipe or several pipes may converge transporting
the slurry. The width of the cross section of the supply channel is
preferably equal to the width of the inlet.
[0044] The feeding channel may be located above the casting box,
for example facing the top portion of the casting box, which is
preferably open or it includes an aperture. The feeding channel may
face the slurry present in the casting box. The slurry falls from
the feeding channel into the casting box in a "free fall" governed
by gravity. The slurry may fall onto the already supplied slurry or
onto a sidewall of the casting box, where it slides to reach the
already supplied slurry.
[0045] The feeding channel may be connected to a sidewall of the
casting box. In this case, the inlet for the slurry includes an
aperture formed in a sidewall of the casting box. The feeding
channel in this configuration is preferably substantially
horizontal or slightly tilted from an horizontal plane.
[0046] The casting box includes a plurality of fins positioned in
the feeding channel. The fins change the flow path of the slurry
flowing into the feeding channel. The fins therefore divert the
slurry from a substantially "linear" flow, that is a flow along a
single substantially straight direction, to a more complex path
because the slurry has to meander through the various surfaces
defined by the fins. In this way, if in the feeding channel slurry
from different pipes arrives, the fins allow a mixing and merging
of the different incoming flows in a single more homogeneous
one.
[0047] Without being bound by theory, the slurry has probably a
shear-thinning behaviour, that is, there is an inverse proportion
between its natural viscosity and the shear strain imposed. Thus, a
good mixing of the slurry inside the casting box may be beneficial
in the manufacturing process, in particular to control the
thickness of the cast sheet. For this reason, preferably, fins
which affect the flow of the slurry are inserted in the feeding
channel. The fins, which may have a blade-like form, advantageously
work as a mass distributor, as well as static mixing elements, as
the slurry during its flow has to contour those fins, dispersing
itself and creating non-linear flows. The slurry therefore has a
"complex local movement" around the fins and at the same time an
overall global movement flowing outside the channel into the
casting box. A better mixed slurry flowing inside the casting box
allow obtaining a more homogenized slurry present in the casting
box.
[0048] The specific geometry, size, number and relative proximity
between the fins enable to define their effects in the flow of the
slurry. These parameters may be designed by computer simulations,
given the outline of the feeding channel and the characteristics of
the slurry.
[0049] The portion of the feeding channel containing the path
diverting fins may be detached and removed from the slurry supply
element.
[0050] The fins have a dimension which is much smaller than the
other two, which is their thickness. The fins are preferably
blade-like elements which are positioned in the feeding channel
where they can interfere with the flow of the slurry. Each fin
defines two substantially opposite main surfaces and a thin lateral
surface connecting the two.
[0051] The fins may protrude from one of the walls of the feeding
channels, for example they can be fixed on such a wall and extend
from an internal surface of the wall in contact to the slurry.
Preferably, the main surfaces of each fin are substantially
perpendicular to the wall of the feeding channel. The fins may have
a height equal to a dimension of the channel, so the fins may
contact two opposite walls of the channel.
[0052] Preferably, the longest dimension, such as the height or
width, of the fins is comprised between about 2 centimeters and 10
centimeters, more preferably it is comprised between about 4
centimeters and 8 centimeters.
[0053] In case many fins are present, all fins can be joined by a
connecting element, such as a bar or a frame. The bar or frame may
also connect the fins in groups. Each group might have a single
connecting element different from the other groups. The connection
is useful in order to remove all fins at the same time for cleaning
or repairing purposes. Further, it is useful so that the position
of all fins can be regulated at the same time.
[0054] The fins may be attached directly to the walls of the
channels. The fins may be connected by the bar or frame and the bar
or frame may be attached to the walls and the fins themselves may
not be in contact with the walls of the channel.
[0055] Each of the fins may define an axis or direction. The fins
on a top view form substantially a curve. This curve has a first
and a second end. The direction defined by the fins, thus their
axis, is given by a line joining the first and the second end.
[0056] Preferably, a sub-group of the path diverting fins includes
fins having parallel axis one to the other. Preferably, the fins
form groups where all fins "point" toward the same direction. For
example, the path diverting fins may be divided in rows, and each
row includes fins having parallel axes among each other. The rows
of fins are positioned one downstream the other along the direction
of flow of the slurry, for example, if a first and a second row of
fins are present, the first row of fins is located downtream the
second row in the direction of flow of the slurry.
[0057] The fins are preferably curved, that is, they define a
concave portion or a convex portion. The fins may have more than a
concavity. In a top view, the fins therefore may define a C shape,
a S shape or similar. They can also be planar. The referred
potential standard shapes of the cross-sections of the blades/fins
are the ones commonly used for similar purposes, namely to create
the required "deviation" or reorientation of the slurry in each
specific spot, and then the combination of those. In terms of
materials, fins are preferably realized in metal, more preferably
in hard metallic alloys, such as stainless steel hard alloys.
Alternatively or in addition, fins may include hardened surfaces,
or other materials that have high resistance to the abrasion of the
slurry, due to the high content of silica of the tobacco particles
and its known abrasion effect in all types of materials, including
metals. The "hard" material or coating is used because of the wear
caused by the slurry and the nicotine content of the slurry, which
is also chemically aggressive to materials in general.
[0058] "Longitudinal shading bands" which may appear in the cast
sheet without the presence of fins may be not present when fins are
located in the casting box. The different incoming flows of slurry
are mixed together by the fins and a single more homogeneous flow
is created.
[0059] Preferably, the slurry supply element includes a tapered
portion. More preferably, the path diverting fins are positioned
downstream the tapered portion in the supply direction. In this
way, it is relatively easy to adjust the set-up for production, as
well as to clean out the inside of the casting box.
[0060] Preferably, the feeding channel defines a channel width and
the path diverting fins are distributed along the width of the
channel. The width is a direction substantially perpendicular to
the casting direction. Advantageously, the whole slurry is diverted
by the fins so that a single homogeneous flow exits the feeding
channel.
[0061] Preferably, the path diverting fins comprise a plurality of
curved fins. Preferably, the fins are not flat, but they are
curved. The main surfaces of the fins thus are curved surface. The
curvature may be used to change the direction of the flow of the
slurry in a plurality of different directions, depending on the
surface orientation of the fin hit by the slurry.
[0062] Preferably, the plurality of curved fins is arranged in at
least one row. More preferably, the curved fins of a same row have
equally oriented concavity. More preferably, all fins in the same
row have parallel axes. Preferably, many fins are present. More
preferably, the fins are arranged along the whole width of the
channel, which is generally similar to the width of the casting
box, which is substantially equal to the width of the casting
blade, so that all the slurry is affected by the fins presence.
Preferably, the fins are disposed one adjacent to the other leaving
a space therebetween so that the slurry can flow therethrough. The
slurry therefore preferably flows through different channels, each
channel being formed by two surfaces, one of a fin and one of the
neighbour fin.
[0063] Preferably, each of the curved fins defines a concavity, the
curved fins of a same row having equally oriented concavity.
"Equally oriented concavity" means that all fins in a row have
their concavity on the same side of their axis. The fins may have
more than a single curvature. The fins of a row of fins, which
preferably spans the whole width of the casting box, have
preferably their curvatures pointing all in the same direction.
[0064] Preferably, the curved fins of two adjacent rows have their
concavity oppositely oriented. The movement imparted to the flow by
the fins is "as complex as possible" so that it deviates from
linearity and a better mixing is obtained.
[0065] Preferably, the casting box includes sidewalls and the
slurry supply element defines an inlet for the slurry, the inlet
for the slurry being formed in one of the lateral walls. The slurry
enters into the casting box via an aperture formed in one of the
sidewalls.
[0066] Preferably, the slurry supply element defines an inlet for
the slurry, the inlet for the slurry being positioned above or at a
top portion of the casting box. The slurry is supplied from above
the casting box and falls into the casting box by gravity.
[0067] The invention also relates to a method to cast a sheet of a
material containing alkaloids, the method comprising: providing a
casting box; providing a casting element connected to the casting
box; providing a movable support facing the casting element;
providing a slurry supply element defining a feeding channel;
providing path diverting fins positioned within the feeding
channel; introducing the slurry into the casting box along a supply
direction trough the feeding channel; and casting the slurry on the
movable support by means of the casting element.
[0068] Preferably, the casting element is a casting blade.
[0069] The advantages of the method have been already outlined when
describing the apparatus and are not going to be repeated.
[0070] Preferably, the step of feeding the slurry inside the
casting box comprises introducing the slurry in the casting box
along a supply direction forming an angle with a horizontal plane
comprised between about -45 degrees and about +45 degrees. A
horizontal feeding of the slurry may provide for a better control
of the flow of slurry inside the casting box because it is
regulated by the applied pressure and not by gravity such in a
"free-fall" case. Thanks to a feeding channel which is not
vertical, the formation of air bubbles inside the casting box is
reduced or minimized; furthermore the slurry contained in the
casting box is not affected by the potential energy of the falling
slurry and this may entail a more homogeneous (content and
thickness) cast leaf due to a constant pressure condition within
the casting box.
[0071] Preferably, the step of feeding the slurry inside the
casting box comprises introducing the slurry in the casting box
along a supply direction forming an angle with a vertical plane
comprised between about -15 degrees and about +15 degrees.
[0072] Alternatively, the slurry may enter the casting box from
above, that is, at the end of the feeding channel, there is a fall
in the air of the slurry, which reaches the casting box positioned
below. In this configuration, preferably the feeding channel is
substantially vertical.
[0073] Preferably, the method includes the step of adjusting a
position of the path diverting fins shifting the path diverting
fins along the supply direction depending on parameters of the
slurry or of the cast sheet. Preferably, the method includes
adjusting an orientation of the path diverting fins with respect to
the supply direction depending on parameters of the slurry or of
the cast sheet. The position and the orientation of the fins can be
regulated depending on the characteristics of the slurry and the
desired characteristic of the cast sheet. The fins can be
re-oriented and moved from and towards the inlet, shifting of a
given amount.
[0074] Preferably, the cast sheet of a material containing
alkaloids includes a homogenized tobacco sheet.
[0075] The invention may also relate to a casting apparatus to cast
a sheet of a material, the casting apparatus including: a casting
box apt to contain a slurry to be cast to form the sheet; a slurry
supply element defining a feeding channel apt to introduce the
slurry into the casting box in a supply direction; path diverting
fins positioned within the feeding channel, the path diverting fins
being apt to come into contact with the slurry inside the feeding
channel; a movable support; and a casting element apt to cast the
slurry contained in the casting box onto the movable support so as
to form the cast sheet.
[0076] The invention may also relate to a method to cast a sheet of
a material, the method comprising: providing a casting box;
providing a casting element connected to the casting box; providing
a movable support facing the casting element; providing a slurry
supply element defining a feeding channel; providing path diverting
fins positioned within the feeding channel; introducing the slurry
into the casting box along a supply direction trough the feeding
channel; and casting the slurry on the movable support by means of
the casting element.
[0077] Further advantages of the invention will become apparent
from the detailed description thereof with no-limiting reference to
the appended drawings wherein:
[0078] FIG. 1 is a schematic lateral section view of an apparatus
for the production of a web of a material containing alkaloids;
[0079] FIG. 2 is a schematic lateral section view of a further
embodiment of an apparatus for the production of a web of a
material containing alkaloids; and
[0080] FIG. 3 is a schematic perspective view of a portion of the
apparatus of FIG. 2.
[0081] With reference to FIG. 1, a first embodiment of a casting
apparatus for the production of a cast web of a material containing
alkaloids according to the present invention is represented and
indicated with reference number 100. Only a portion of the casting
apparatus 100 is shown in FIG. 1.
[0082] In particular, the casting apparatus 100 is adapted for the
production of a cast web of a homogenized tobacco material 11.
[0083] The casting apparatus 100 comprises a casting box 10
containing slurry 18, a movable support 2, and a casting blade 1,
wherein the casting blade 1 casts slurry 18 contained in the
casting box 10 onto the movable support 2 so as to form the cast
sheet of homogenized tobacco material 11. The movable support 2
defines a casting direction depicted by arrow 24 in FIG. 1.
[0084] Slurry 18 from buffer tanks (not shown in the drawings) is
transferred into the casting box 10 usually by means of a pump (not
shown in the drawings). Preferably, the pump comprises a control
(not visible in the drawing) of flow rate to control the amount of
slurry 18 introduced in the casting box 10. The pump is
advantageously designed to ensure that slurry transfer times are
kept to the minimum necessary. The pump is fluidly connected, for
example by means of a slurry supply element 5, to the casting box
10 so as to feed the same with the slurry 18.
[0085] The casting box 10 comprises sidewalls including a first and
a second opposite walls 3, 4. The casting blade 1 is associated to
the casting box 10 at the second wall 4. The casting box 10 is
generally defined by four side walls, i.e. the first and second
opposite walls 3, 4 and a third and a fourth opposite walls (not
shown in the figures), which connect the first and second opposite
walls 3, 4.
[0086] The movable support 2 comprises for example a continuous
stainless steel belt including a drum assembly. The drum assembly
includes a main drum 21 located below the casting box 10 which
moves the movable support 2. Preferably, the casting box 10 is
mounted on top of the main drum 21.
[0087] The slurry is casted on the steel belt--at the drum
21--through the casting blade 1, which creates a continuous sheet
of homogenized tobacco material. In order for the slurry to reach
the casting blade and thus the movable support, the casting box 10
has an opening or aperture 17 in correspondence of its bottom and
the opening 17 extends along a width of the casting box 10. The
opening 17 is positioned over and in proximity of the drum 21.
[0088] The top portion of the casting box 10 in this embodiment is
open.
[0089] The movement of the steel belt 2 forwards the slurry 18
towards the casting blade 1, for example towards the second wall 4.
The casting blade 1 casts a part of the slurry 18 on the steel belt
2, while the remaining majority of the slurry 18 turns back and
recirculates inside the casting box 10.
[0090] The casting blade 1 has a dominant dimension which is its
longitudinal width. The casting blade 1 is for example
substantially rectangular.
[0091] The casting blade 1 is attached to the casting box 10
preferably by means of an adjustable board 8 operated by an
actuator 9 which allows a precise control of the position of the
casting blade 1, in particular of its distance with respect to the
movable support 2.
[0092] Between the casting blade 1 and the movable support 2 a gap
is present, the dimensions of which determine--among others--the
thickness of the cast web of homogenized tobacco material 11.
[0093] The slurry supply element 5 for the transfer of slurry 18
into the casting box, may have different positioning and shapes. In
the embodiment of FIG. 1, the fluid supply element 5 includes a
channel 15 which defines an inlet 90. The inlet 90 is substantially
an aperture formed on the sidewall 3 of the casting box 10.
Preferably, channel 15 is arranged substantially horizontally, so
that at the inlet 90 the direction of the flow of slurry is
substantially horizontal.
[0094] Further, casting box 10 includes a plurality of fins located
in the channel 15. The fins are arranged in two substantially
parallel first and second row, the second row being upstream of the
first row in the direction of flow of the slurry. Any number of
rows is possible. The fins of the first row are all indicated with
19 and the fins of the second row are all indicated with 20. The
height of the fins is substantially similar to the height of
channel 5.
[0095] Each fin 19, 20 of the first or second row on a top view
defines a curved shape, the concavity of the fins having the same
orientation in each row. FIG. 3 shows the first and second rows of
fins clearly. Each fin 19, 20 has a C shape, where the concavity of
the C is positioned substantially facing the main direction of flow
of the slurry. Fins all have the same shape and all defines a major
dimension. Each fin defines an axis, which is the continuation of a
line joining a first and second end of the fin in a top view. In
each row the fins are preferably parallel, that is, preferably they
have parallel axes.
[0096] A first and a second adjusting elements, not visible in the
drawings, may operate fins in order to change their position. First
adjusting element may rotate the fins around their axis so that the
orientation of each axis changes, while second adjusting element
may change their exact position along the channel 15, closer or
more remotely from inlet 90.
[0097] Slurry supply element 5, upstream the fins 19, 20 in the
direction of flow of the slurry 18 in the channel 5, also
preferably includes a tapered portion 6.
[0098] In FIGS. 2 and 3, a second embodiment of an apparatus 101
for the casting of a sheet 11 is visualized. The difference between
this embodiment and the previous one lies in the slurry supply
element 50.
[0099] The slurry supply element 50 comprises a plurality of pipes
80 and a distributor 51. The slurry is supplied from a single
tubular pipeline (not visible) which is then split in the plurality
of pipes 80. The flow of slurry from each pipe 80 opens up into a
triangular shape inside distributor 51 in order to adapt and cover
the total width of the casting box (see for example FIG. 3).
Distributor 51 defines channel 15 including the fins 19, 20, having
inlet 90. The slurry 18 is dropped in a continuous or discontinued
way directly to the casting box from above, as visible in FIGS. 2
and 3. During the dropping from inlet 90 of the channel 15, the
slurry drops may touch the sidewall 3 or not. In case it touches
the sidewall 3, the slurry slides onto the same.
[0100] Fins 19, 20 are positioned inside the channel 15 in an
identical manner as in the channel of the previous embodiment.
Channel 15 of this embodiments is similar to channel 15 of the
previous embodiment, just differently oriented, that is, it is
substantially vertical instead of horizontal.
[0101] FIG. 3 shows the effect of the fins on the slurry incoming
from the different piping 80. From a plurality of flows from
different pipes 80 opened by distributor 51, a single flow is
obtained thanks to the channel 15.
[0102] The functioning of the casting apparatus 100-101 is as
follows. A slurry 18, formed preferably mixing and combining
tobacco powder and other ingredients, is transferred from a buffer
tank (not shown) using for example in line mixers (also not shown)
to the casting apparatus 100-101 and in particular inside the
casting box 10.
[0103] The slurry 18 is supplied for example by an horizontal
channel 15 having the inlet 90, which is positioned at a rear or
upstream side of casting box 10 (at the sidewall 3 of the casting
box 10). The casting blade 1 is located at a front or downstream
side of the casting box 10, near the sidewall 4. Alternatively,
slurry is distributed from above, for example it enters the casting
box via the open top portion of the same through a substantially
vertical channel 15, and falls on the casting box 10 and/or slides
along sidewall 3. In any case, the slurry has to pass through fins
19, 20 and homogenize.
[0104] Further, preferably the level of slurry in the casting box
10 is monitored. Preferably, also the moisture of the slurry inside
the casting box 10 is monitored. Further, preferably, the density
of the slurry 18 is monitored. The monitoring of the above
mentioned parameters is performed by means of suitable sensors.
[0105] The thickness of the web of homogenized tobacco material and
grammage controlled by nucleonic gauge immediately after casting
are preferably continuously monitored and feedback-controlled using
slurry measuring device.
[0106] The casting is performed by means of casting blade 1 forming
a gap with the movable support 2, gap that can also be feedback
controlled.
[0107] Further, the cast web undergoes a drying step by means of a
drying apparatus (not visible in the drawings). The drying
apparatus includes a plurality of individual drying zones. Each
drying zone preferably includes steam heating on the bottom side of
the support and heated air above the movable support 2 and
preferably also adjustable exhaust air control. Within the drying
apparatus, the homogenized tobacco web is dried to desired final
moisture on the support 2.
[0108] The drying step includes preferably a uniform and gentle
drying of the cast web in an endless, stainless steel belt dryer
with individually controllable zones. During the drying, a
monitoring step of the cast web temperature at each drying zone to
ensure a gentle drying profile at each drying zone is preferably
performed. The cast web is dried to desired final moisture on the
steel belt 2 with steam pan heating from bottom and top air drying.
Every drying zone is equipped with steam flow and pressure control
and air temperature and air flow are fully adjustable to provide
the desired drying profile and ensuring product residence time is
respected.
* * * * *